TITLE: GCN CIRCULAR NUMBER: 39988 SUBJECT: GRB 250331E: Fermi GBM Final Real-time Localization DATE: 25/03/31 22:57:04 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 22:46:32 UT on 31 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250331E (trigger 765153997.78765 / 250331949). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 196.6, Dec = -27.7 (J2000 degrees, equivalent to J2000 13h 06m, -27d 41'), with a statistical uncertainty of 14.0 degrees. The angle from the Fermi LAT boresight is 73.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/q... The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/q... The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/q... View this GCN Circular online at https://gcn.nasa.gov/circulars/39988. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...